cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A156057 Decimal expansion of log(3)/2.

Original entry on oeis.org

5, 4, 9, 3, 0, 6, 1, 4, 4, 3, 3, 4, 0, 5, 4, 8, 4, 5, 6, 9, 7, 6, 2, 2, 6, 1, 8, 4, 6, 1, 2, 6, 2, 8, 5, 2, 3, 2, 3, 7, 4, 5, 2, 7, 8, 9, 1, 1, 3, 7, 4, 7, 2, 5, 8, 6, 7, 3, 4, 7, 1, 6, 6, 8, 1, 8, 7, 4, 7, 1, 4, 6, 6, 0, 9, 3, 0, 4, 4, 8, 3, 4, 3, 6, 8, 0, 7, 8, 7, 7, 4, 0, 6, 8, 6, 6, 0, 4, 4
Offset: 0

Views

Author

Jonathan Vos Post, Feb 03 2009

Keywords

Comments

Culler & Shalen show a bound of log(3)/2 on maximal injectivity under certain circumstances, see links.
Equals arctanh(1/2), the rapidity of an object traveling at half the speed of light. - Sean Stroud, May 13 2019

Examples

			0.54930614433405484569762261846...
		

Crossrefs

Cf. A000045, A002391 (decimal expansion of natural logarithm of 3).

Programs

Formula

Equals arctanh(1/2) = arccoth(2) = Integral_{x>2} 1/(x^2-1) dx. - Jean-François Alcover, Jun 04 2013
From Amiram Eldar, Aug 05 2020: (Start)
Equals Sum_{k>=0} 1/((2*k+1) * 2^(2*k+1)).
Equals Integral_{x=0..oo} 1/(exp(x) + 2) dx. (End)
Equals Sum_{k>=1} arctanh(1/Fibonacci(2*k+2)) (Melham and Shannon, 1995). - Amiram Eldar, Jan 15 2022
log(3)/2 = Sum_{n >= 1} 1/(n*P(n, 2)*P(n-1, 2)), where P(n, x) denotes the n-th Legendre polynomial. The first 10 terms of the series gives the approximation log(3)/2 = 0.54930614433(10...), correct to 11 decimal places. - Peter Bala, Mar 16 2024

Extensions

All digits were wrong. Corrected by N. J. A. Sloane, Feb 05 2009
Offset 0 from Michel Marcus, May 13 2019